Internal Heat Gains: People, Lighting, Equipment
The heat the building makes inside: occupant sensible and latent gain from the activity-level rate, plus lighting and plug load at 3.412 Btu/h per watt, scaled by the use factor actually on. The sensible/latent split sets the coil's job - a packed conference room flips from sensible-heavy to latent-heavy, and that latent is moisture a sensible-only 'more airflow' fix never removes. The per-person rates come from the ASHRAE activity table. One Manual J component, not the stamped load sheet.
Formula and source
q_people_sensible = occupants x sens_per_person; q_people_latent = occupants x lat_per_person; q_lighting = lighting_w x 3.412 x use_factor; q_equipment = equipment_w x 3.412 x use_factor; q_sensible = q_people_sensible + q_lighting + q_equipment; q_latent = q_people_latent; q_total = q_sensible + q_latent.
ASHRAE / ACCA Manual J internal-gain method (occupant sensible and latent from the activity-level table, lighting and equipment at 3.412 Btu/h per watt), by name; the 3.412 is the watt-to-Btu/h conversion.
Audience
This tile is built for hvac and the adjacent professions in the HVAC group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.